This history recounts the development of nuclear physics from the discovery of the neutron in the early 1930s through the 1960s. Based on over 700 published papers, it contains four sections: from the discovery of the neutron to nuclear fission, nuclear instruments, nuclear models, and nuclear reactions. Writing for people who are interested in the history of science, the author develops the topics in detail through accessible language, covering the scientific principles, the technology and historical development of the field.